Tripper bar mounting arrangement for multi-phase circuit breaker



Jan. 27, 1970 MUL'I'I-PHASE CIRCUIT BREAKER 5 Sheets-Sheet 1 Filed July 11, 1968 N H b H Jan. 27, 1970 A. STROBEL 3,492,610

v -TRIPPER BAR MOUNTING ARRANGEMENT FOR MULTI-PHASE CIRCUIT BREAKER Filed July 11, 1968 5 Sheets-Sheet 2 Jan. 27, 1,970 A. STROBEL 3,492,610

TRIPPER BAR MOUNTING ARRANGEMENT FOR MULTI-PHASE CIRCUIT BREAKER Filed July 11, 1968 5 Sheets-Sheet 3 f INVENTOR. 141 5:27- 7".(41321 4972-9045/9 564g seej JEFF! Jan. 27, 1970 A. STROBEL 3,492,610

TRIPPER BAR MOUNTING ARRANGEMENT FOR MULTI-PHASE CIRCUIT BREAKER Filed July 11. 1968 5 Sheets-Sheet 4 Jan. 27, 1970 A. STROBEL TRIPPER BAR MOUNTING ARRANGEMENT FOR MULTI muss CIRCUIT BREAKER Filed July 11, 1968 5 Sheets-Sheet 5 772 4514 Fnaagr United States Patent 3,492,610 TRIPPER BAR MOUNTING ARRANGEMENT FOR MULTI-PHASE CIRCUIT BREAKER Albert Strobe], Cherry Hill, N.J., assignor to I-T-E Imperial Corporation, Philadelphia, Pa., a corporation of Delaware Filed July 11, 1968, Ser. No. 744,125 Int. Cl. H01h 75/00, 77/00 US. Cl. 335-46 8 Claims ABSTRACT OF THE DISCLOSURE A trip unit assembly of a multi-phase molded case circuit breaker utilizing a mounting arrangement for the tripper bar which is capable of withstanding higher impact shock forces. The pivotal mounting of the tripper bar includes the main centrally located bearings and an additional pair of outboard pivots. The outboard pivots include a compensating structure to allow for up to a predetermined degree of misalignment between the various components.

My invention relates to molded case circuit breakers, and more particularly to a trip unit assembly having the ability to withstand high impact forces applied from different directions.

Automatic m-ulti-phase molded case circuit breakers are typically provided with a trip unit assembly having a pivotally mounted tripper bar for transmitting the actuation of any of the individual phase fault sensing means to the common operating mechanism. Such a circuit breaker is typically shown in US. Patent No. 3,319,195. A very common type of commercial circuit breaker of this type is a three-phase unit, which includes transversely adjacent compartments. Each of the compartments includes individual phase conductors, including a pair of operating contacts. A common operating mechanism is provided for all of the contacts. The operating mechanism typically includes a normally latched member. This normally latched member is operatively connected to the tripper bar of the trip unit assembly. The trip unit assembly for such a circuit breaker includes an individual fault sensing means for each phase. The tripper bar is normally positioned in a manner that serves to maintain the latch of the operating mechanism. However, upon the sensing of a fault condition in any one of the phases, the tripper bar is rotated in a direction which serves to defeat the latched engagement of the latchable member, and thereby serves to automatically move the circuit breaker operating mechanism to the tripped open position.

In certain application (e.g., shipboard installation), the molded case circuit breaker may be subjected to severe shock forces. Such shock forces may tend to cause rotation of the tripper bar in a direction to defeat the latched engagement of the operating means, thereby erroneously moving the circuit breaker to the tripped open condition; Common methods to avoid and counteract rotation of the tripper bar under shock are the balancing of the bar, the use of an inertia weight which returns the tripper bar to its starting position without permitting defeat of the latchable member, and the use of a resilient stop which absorbs the shock from other components rather than transmitting it to the tripper bar.

While the above-noted methods have served to considerably improve the shock resisting capabilities of the circuit breaker, it has been experienced that under certain conditions of shock loading the tripper bar may still move in a direction to cause ultimate defeat of the operating mechanism latch. This results from the need to provide the bearing supports for the tripper bar relatively close together, in order to keep them in proximity to the latching system. Thus, the tripper bar is normally pivotally mounted by a pair of bearings at the central region thereof, which leaves a substantial length of the tripper bar freely extending outward from the main bearing supports. Under high impact, these end portions can whip sutliciently to unbalance and rotate the tripper bar and cause latch disengagement, regardless of the other precautions which may be built into the tripper bar structure.

I solve this problem by providing a pair of additional outboard bearing supports at the end regions of the tripper bar. During high impact, these hearings keep the bar from whipping and from rotation due to lack of balance, without impairing rotation of the tripper bar under normal operating conditions.

Since the addition of these outboard bearings results in four individual bearings supporting the tripper bar, a problem results in ensuring proper alignment of these bearings to prevent binding of the tripper bar pivotal movement. That is, in accordance with normally experienced manufacturing tolerances, there may be a certain amount of warpage in the tripper bar, as well as in the trip unit base to which the bearings have to be attached. In order to insure proper pivotal movement of the tripper bar, I have found it advantageous to include within the outboard bearings an adjustment means for compensating for misalignment in both a first and second orthogonally related direction within a plane perpendicular to the tripper bar axis.

I provide a simple means for aligning the tripper bar pivots by utilizing a bearing plate which will be selfaligned to the tripper bar bearing pin, and may then be fastened in place. The bearing plate includes a close tolerance hole to match the bearing pin extending outward of the tripper bar, and lying along the pivotal axis. The bearing plate has one or more tapped holes which receives a fastening screw. The screw extends through oversized clearance openings of a complementary stationary support bracket, thereby permitting relative movement between the bearing plate and support bracket, in accordance with the clearance dimension of such oversize holes. After the tripper bar is assembled within the trip unit assembly, the screws holding the bearing plate to the bearing bracket are tightened, thereby bringing the bearing plate into intimate surface engagement with the stationary support bracket, for preventing further movement of the bearing plate.

It is therefore seen that my invention provides an improved mounting arrangement for the tripper bar of a circuit breaker trip unit assembly, which provides increased resistance to shock loading and prevents binding of the normal tripper bar movement.

It is therefore a primary object of my invention to provide an improved shock resistant mounting for the tripper bar of a multi-phase circuit breaker trip unit.

Another object of my invention is to provide within a multi-phase circuit breaker a common tripper bar which includes outboard pivot means in addition to the centrally located main pivot means.

A further object of my invention is to provide such a pivotal mounting for a circuit breaker common tripper bar, in which the auxiliary outboard pivot means includes an adjustment means for compensating for misalignment, resulting from tripper bar warpage and the accumulation of manufacturing tolerances.

An additional object of my invention is to provide within the trip unit portion of a three-phase molded case circuit breaker an improved mounting for the tripper bar, which includes in addition to the main pair of pivots centrally located about the intermediate phase an additional pair of outboard pivots at the free ends of the tripper bar, located at the transversely outward extremes of the outer phases.

These as well as other objects of my invention will be readily apparent upon a consideration of the following description and drawings in which:

FIG. 1 is a plan view of a three-phase molded case circuit breaker having a trip unit assembly employing the instant invention.

FIG. 2 is a cross-sectional view along the line 22 of FIG. 1, showing the central phase including the circuit breaker operating mechanism.

FIG. 3 is a cross-sectional view, along the line 3-3 of FIG. 1, and showing the trip unit assembly.

FIG. 4 is a cross-sectional View along the line 44 of FIG. 3, and showing the auxiliary pivotal mounting at one of the tripper bar ends.

FIG. 5 is an exploded perspective view of this pivotal mounting.

FIG. 6A shows enlarged a portion of FIG. 4, with the bearing plate being moved to a position corresponding to alignment between the interconnected parts.

FIG. 6B corresponds to FIG. 6A, but shows the bearing plate being moved to compensate for misalignment in the vertical direction.

FIG. 6C shows the bearing plate being moved to compensate for misalignment in the horizontal direction.

FIG. 7 is a cross-sectional view along the line 77 of FIG. 3, and shows the auxiliary bearing support at the other end of the tripper bar.

FIG. 8 is an exploded perspective view of the pivotal mounting.

FIGS. 9A, 9B and 9C show enlarged a portion of FIG. 7, representing the movement of the bearing plate, corresponding to conditions similar to that of FIGS. 6A, 6B and 6C respectively, at this end of the pivot bar.

FIG. 10 is a cross-sectional view along the line 1010 of FIG. 3, and shows the inertia weight utilized to counteract shock-induced movement of the tripper bar.

Now referring to the figures, circuit breaker 10, wherein my invention is incorporated, is shown as a commercially available three-phase molded case unit of the general type more fully described in above-referred to US. Patent No. 3,319,195. It should be naturally understood that the novel concepts of this invention may be incorporated in numerous other frame sizes and types, with this embodiment being merely for illustrative purposes.

Circuit breaker 10 is assembled within a housing comprising molded base 11, separated into compartments 12, 13 and 14, for locating the operating members of each of the phases. The adjacent compartments are separated by housing walls 15 and 16. Main cover assembly 17 and end covers 18 similarly include barriers for maintaining the transversely adjacent and longitudinally extending compartments of the housing.

Each of the compartments 12, 13 and 14 includes an electrically isolated current carrying path. The current.

carrying members of each of these paths are identical, with the center phase being shown in FIG. 2. The center phase also includes the circuit breaker operating mechanism generally shown as 32, to provide coordinated operation between all three of the phases.

The current carrying path in each phase between the line terminal strap 20 and the load terminal strap 21 is as follows (see FIG. 2). The line terminal strap 20 includes at its inward end the main and arcing stationary contacts 22, 23. With the circuit breaker in the ON condition, these contacts are in engagement with cooperating movable contacts 24, 25, respectively, carried by contact arms 26 and 27. The current path then proceeds through flexible braids 28, to the contact carrier strap 29. The replaceable trip unit assembly 100, incorporating my invention, is inserted in the circuit breaker between the contact carrying strap 29 and load terminal strap 21. The trip unit assembly 100 includes a current carrying strap 102, connected at its inward end by bolt 114 to the circuit breaker contact carrying strap 29, and connected at its outward end to the circuit breaker line terminal strap 21 by bolt means 112.

Circuit breaker operating mechanism 32 is of the quick make-break overcenter toggle type for rapidly moving the contact arms 26 and 27 between their engaged and disengaged positions. For present purposes, it is sufficient to understand that the movement of the circuit breaker to the manual OFF condition is accomplished by handle and movement to the trip condition of FIG. 2 automatically results from the disengagement of the cradle latch tip 34 from latching bracket extension 101 of the trip unit assembly 100. The disengagement of the latch is effected by rotation of the trip unit assembly tripper bar 104 counter-clockwise from the condition shown in FIG. 2. That is, under normal operating conditions, there will be a latched engagement between 34 and 101, thereby serving to maintain the circuit breaker contact pairs in their engaged or ON condition. When the tripper bar 104 is moved counter-clockwise, this serves to defeat the latched engagement, and thereby automatically move the contacts to their disengaged condition via tie bar 33.

The counter-clockwise rotation of the tripper bar 104 is obtained responsive to a predetermined fault condition occurring in any of the individual phases. Accordingly, the trip unit assembly includes an individual fault sensing means associated with each of the individual phases. This fault condition sensing means may typically include both an overload responsive bimetal, and instantaneous magnetically actuated means.

In the illustrative embodiment, the overload responsive means is of the type which is the subject of my US. Patent No. 3,305,653, and includes an elongated bimetal 103 connected to the current carrying strap 102 by flexible shunt member 105. Upon the occurrence of a sustained overload condition, in accordance with the calibrated characteristics of bimetal 103, it will deflect to the left, as shown in FIG. 2, to thereby engage calibrating screw 106 mounted to the tripper bar 104, serving to rotate the tripper bar 104 counter-clockwise.

The magnetically actuated fault sensing portion is provided by assembly generally shown as 120, which is the subject of copending US. patent application Ser. No. 744,166 filed of even date herewith. Assembly includes a stationary U-shaped magnet 121, and armature member 124. Upon the occurrence of a predetermined fault condition, armature 124 as drawn downwardly against the pole faces of magnet 121. Armature member 124 has an actuating rod 126 secured thereto, such that the rod 126 undergoes a similar downward movement. An adjusting actuating means 125 is threadably retained on rod 126, and positioned such that the downward movement of armature induced movement of the rod 126 serves to engage actuating extension 127 of the tripper bar, thereby providing counterclockwise tripping movement thereof. An externally accessible calibration adjustment 130 of the type which is the subject of US. Patent No.;

3,302,140 is also provided to permit an operator adjust ment of the instantaneous trip pickup point.

The tripper bar 104 is normally attached to the base 122 of the trip unit assembly, by a pair of pivot points centrally located close to latching bracket extension member 101. This pivot means is provided with respect to a pair of centrally located bearing pins 132, 134. These bearing pins are located within close tolerance apertures 138, 139, without arms 133, 135, respectively, of bracket member 137 utilized for mounting the trip unit assembly to the circuit breaker base. Bracket 137 is, in turn, securably and stationarily mounted to the molded support 122 of the trip assembly 100.

The tripper bars of such molded case circuit breaker trip unit assemblies have previously included only the centrally located bearing pins 132, 134 and their associated mounting. Thus, a substantial length of the tripper bar extends from these bearing means to the end extremes 136 and 138. Under conditions of severe shock loading, this unsupported length of tripper bar can whip sufficiently to unbalance and rotate the tripper bar .104 to move latching extension bracket 101 and defeat the latched engagement of cradle tip 34. My invention is directed to the utilization of improved auxiliary bearing pivots at these ends 136 and 138 to avoid this problem.

The shock resistant tripper bar assembly, to which my invention is directed, will generally also include an inertia weight 140, as best shown in FIG. 10. Inertia weight 140 is mounted to bracket 142, and operates in conjunction with lever extension 144, secured to the tripper bar 104. The inertia weight includes a pair of outwardly extending actuating members 146, 148 at diametrically opposed regions. The inertia weight is biased counterclockwise by an axially located spring the end of which is shown at 141. By virtue of the counter-clockwise bias of inertia weight 140, actuating member 148 thereof will normally abut surface 154 of the lever extension 144. Should a shock force occur tending to rotate the tripper bar counter-cockwise (in the trip direction), lever extension surface 154 will transmit the impact to actuating pin 148 in the form of a hammer blow, and the inertia disk will rotate clockwise. Pin 148 will move away from surface 154. Pin 146 will move towards surface 152, meet that surface with an impact in clockwise direction, and restore the tripper bar to its starting position without allowing the latch surfaces to disengage.

While the utilization of the inertia weight arrangement, as well as balancing of the tripper bar and the employment of a resilience stop to absorb the shock, has permitted the design of units exhibiting substantial shock distance, they do not avoid the above-noted whipping condition of the tripper bar, resulting from the unsupported substantial free length of the tripper bar. In accordance with my invention, additional bearing pins 160, 162 are provided at the ends 136, 138 of the tripper bar. These bearing pins provide an auxiliary pivotal support for the ends of the tripper bar in a unique manner providing a simplified means for aligning all the bearings.

Referring to FIG. 4, which shows the details of the bearing support at the end 136, a bearing plate 163 is utilized having a close tolerance aperature 164 for receiving the bearing pin 160. Bearing plate 163 includes a pair of tapped apertures 166, for receiving fastening screw members 168. Screw members 168 extend through oversized clearance apertures 169 provided in the support bracket 172. Support bracket 172 is illustratively shown as the same bracket for mounting the trip unit interlocked assembly 175 including actuating member 177. Mounting plate 172 also includes an additional oversized aperture 179, permitting movement of the bearing pin 160, relative to the fixed location of mounting bracket 172.

The clearance provided between apertures 169 and the shank of screws 168 permit a predetermined degree of relative movement between bearing plate 163 and mounting bracket 172. This predetermined degree of movement permits compensation for misalignment, typically resulting from tripper bar warpage or other manufacturing 6 tolerances. Such compensation is typically shown in FIGS. 6A-6C. FIG. 6A represents an aligned condition not requiring compensation. FIG. 6B represents the condition wherein the misalignment of the end bearing is in the vertical direction only. Accordingly, bearing plate 163 is raised vertically with screw 168 at the upper end of aperture 169 to compensate for such misalignment while providing a firm pivotal mounting of the tripper bar end bearing 160. In FIG. 6C, the misalignment is only in the horizontal direction, with the bearing plate 162 showing compensating movement in this direction.

The mounting of the bearing pin 162 at the other end 138 of tripper bar 104 is similarly provided, as shown in FIGS. 7 and 8. A bearing plate includes an aperture 182, in close tolerance relationship with respect to bearing pin 162. Bearing plate 182 includes a pair of tapped apertures 184, which receive the 'screws 186. Mounting bracket 188 includes a pair of oversized apertures 190, so as to permit relative movement with respect to bearing plate 182, to compensate for misalignment. FIGS. 9A, 9B and 90 show such compensating movement when subjected to conditions at that pivot corresponding to the conditions of FIGS. 6A, 6B and 60. That is, in FIG. 9A there is no misalignment; in FIG. 9B the misalignment is solely in the vertical direction; and in FIG. 9C the misalignment is solely in the horizontal direction.

It should also be appreciated that the outboard hearing supports will also permit compensation for misalignment having components in both the vertical and horizontal directions.

It should now be understood that the utilization of the hereindescribed outboard bearings permits the tripper bar to be accurately assembled to the trip unit housing in an extremely simplified manner, While assuring proper pivotal movement thereof without binding. The assembly procedure consists in first loosely assembling the bearing plates 163 and 180 to the bracket members 172 and 188. The bearing plates are then slid over the bearing pins 160, 162 and the brackets 172, 188 are mounted to the trip unit base. The bearings will align themselves with the bearing pins without requiring adjustments. The screws 168, 186 are then tightened. The two outboard bearings will now be aligned with the two previously mounted primary bearings 13-2, 134, thereby assuring reliable non-binding operation of the tripper bar 104 in a manner offering substantially increased resistance to shock impact loading.

It is therefore seen that \my invention provides an improved mounting for the tripper bar, which by the utilization of a pair of adjustable outboard bearings support the free ends of the tripper bar and assure alignment thereof with the main tripper bar bearings.

Although there has been described a preferred embodiment of this novel invention, many variations and modifications will now be apparent to those skilled in the art. Therefore, this invention is to be limited not by the specific disclosure herein but only by the appending claims.

The embodiments of the invention in which an exclusive privilege or property is claimed are defined as follows.

1. A multi-phase molded case circuit breaker, includmg:

a pair of cooperating contacts for each of the phases;

an operating means operatively connected to said contact pairs for simultaneously moving all of said contacts between an engaged and disengaged condition responsive to a fault in any one phase;

said operating means including a normally latched member;

a trip means including an individual fault sensing means for each phase and an elongated tripper bar having opposed first and second ends;

pivot means rotatively supporting said tripper bar for movement about a pivotal axis between first and second positions;

each of said fault sensing means including an actuating means for moving said tripper bar to said second position responsive to actuation of an individual fault sensing means;

said tripper bar including latch defeat means operatively connected to said normally latched member, such that when said tripper bar is in said first position said latch is maintained, and the movement of said tripper bar to said second position defeats the latching of said normally latched member to effect automatic movement of said operating means to the contact disengaged condition;

said latch defeat means located at the central region of said tripper bar;

said pivot means including first and second bearing means closely adjacent the centrally located latch defeat means;

said first bearing means interposed between said first tripper bar end and said latch defeat means;

said second bearing means interposed between said second tripper bar and said latch defeat means;

a substantial length of said tripper bar extending between each of said bearing means and a tripper bar end;

said pivot means including additional first and second outboard pivot means;

said first outboard pivot means including bearing means for pivotally supporting said first tripper bar end, and said second outboard pivot means including bearing means for pivotally supporting said second tripper bar end.

2. A multi-phase molded case circuit breaker, as set forth in claim 1:

said outboard pivot bearing means including adjustment means for providing non-binding pivotal mounting of said tripper bar compensating for alignment between said bearing means of up to a predetermined extent.

3. A multi-phase molded case circuit breaker, as set forth in claim 2:

said adjustment means including means for compensating in both first and second orthogonally related directions within a plane perpendicular to the pivotal axis.

4. A multi-phase molded case circuit breaker as set forth in claim 1:

said outboard pivot means including a bearing plate and stationary support bracket;

a bearing pin extending axially beyond the tripper bar end;

said bearing plate including a bearing aperture rotatively receiving said bearing pin in close tolerance relationship;

said bearing plate including tapped aperture means;

said stationary support bracket including oversize aperture means in registry relationship with said tapped aperture means;

screw means extending through said oversize aperture means and threadedly engaging said tapped aperture means;

said screw means, when tightened, locating said bearing plate in intimate surface engagement with said stationary support bracket for preventing movement of said bearing plate;

said oversize aperture means permitted a predetermined degree of relative movement between said bearing 'plate and stationary support bracket, thereby compensating for misalignment between said bearing pin and said support bracket.

5. A multi-phase molded case circuit breaker, as set forth in claim 4:

said oversize aperture means permitting relative movement of said bearing plate in both a first and'second orthogonally related directions within a plane'perpendicular to the pivotal axis.

6. A three-phase molded case circuit breaker, including transversely adjacent first, second and third compartments for the individual phases:

a pair of cooperating contacts for each of the phases located within the respective compartments;

an operating means operatively connected to all of said contact pairs for simultaneously moving all of said contacts between an engaged and disengaged condition responsive to a fault in any one phase;

said operating means including a normally latched member in said second compartment;

a trip means including an individual fault sensing means located within the compartment of that phase;

an elongated tripper bar extending across said first, second and third compartments, and including a first end located at the transversely outward end of said first compartment, and a second end located at the transversely outward end of said third compartment;

pivot means rotatively supporting said tripper for movement about a pivotal axis between first and second positions;

each of said fault sensing means including an actuating means for moving said tripper bar to said second position responsive to actuation of an individual fault sensing means;

said tripper bar including latch defeat means operatively connected to said normally latched member, such that when said tripper bar is in said first position said latch is maintained, and the movement of said tripper bar to said second position defeats the latching of said normally latched member to effect automatic movement of said operating means to the contact disengaged condition;

said latch defeat means located in said second compartment;

said pivot means including first and second bearing means closely adjacent said latch defeat means;

said first bearing means located in the central region between said first and second compartments;

said second bearing means located in the central region between said second and third compartments;

a substantial length of said tripper bar extending between each of said bearing means and the tripper bar ends;

said pivot means including additional first and second outboard pivot means;

said first outboard pivot means including first bearing means at the transversely outward end of said first compartment for pivotally supporting said first tripper bar end, and said second outboard pivot means including bearing means at the transversely outward end of said third compartment for pivotally supporting said second tripper bar end.

7. A three-phase molded case circuit breaker, as set forth in claim 6:

tionary support bracket for preventing movement of said bearing plate;

said oversize aperture means permitted a predetermined degree of relative movement between said bearing plate and stationary support bracket, thereby compensating for misalignment between said bearing pin and said support bracket.

8. A three-phase molded case circuit breaker, as set forth in claim 7:

said oversize aperture means permitting relative movement of said bearing plate in both a first and second orthogonally related directions within a plane perpendicular to the pivotal axis.

References Cited 5 UNITED STATES PATENTS 2,449,013 9/ 1948 Scott 33546 3,302,140 1/1967 Strobel 335-35 BERNARD A. GILHEANY, Primary Examiner 10 H. BROOME, Assistant Examiner 

